In today's environment, a server computer system often includes several components, such as the server itself, hard drives, or other peripheral devices. These components are generally stored in racks. For a large organization, the storage racks can number in the hundreds and occupy huge amounts of expensive floor space. Also, because the components are generally free standing components (i.e., they are not integrated), resources such as disk drives, keyboards, and monitors cannot easily be shared. Blade servers have been developed to bundle the server computer system described above into a compact operating unit. A blade server may be a high-density, rack-mounted packaging architecture for servers that provides input/output (I/O), systems management, and power to individual blades. Blades may include servers, processor nodes, storage nodes, or other components and may each plug into and operationally connect to the blade server to share in resources such as power, cooling, network connectivity, management functions, and access to other shared resources (such as a front-panel or CD-ROM drive). One feature of blade servers is that individual blades may be ‘hot swapped’ without affecting the operation of other blades in the system. An administrator or other user may simply remove one blade (such as one that is inoperable or that will be replaced) and place another in its place. An example blade server is International Business Machines (IBM®) Corporation's IBM eServer™ BladeCenter® system, a high-density, rack-mounted packaging architecture for servers that provides I/O, systems management, and power to inserted blades.
In server design, as in the design of many other types of computer systems, there is a trend towards higher densities of components. For example, it is often desirable to put a greater number of server blades into a package of given size. Additionally, server designers (similarly to designers of other computer systems) continue to increase performance of server components in order to meet customer needs. In combination, the higher component densities and increased performance of components result in an increased need for cooling of the servers and their components. Such increased cooling needs are likely to continue to rise as component densities and performance both increase. Accordingly, blade servers typically cool their component blades by drawing air through the chassis of the blade server and thus through each blade (or fillers) via the use of blowers in a front-to-back blade cooling pattern. Typically, it is desired for approximately equal airflow to flow through each blade so that each receives sufficient airflow for cooling.
As cooling needs continue to increase, current cooling solutions suffer from problems in some situations. When one or more blades are removed from a blade server, for example, the airflow no longer is evenly distributed across the server as the majority of air entering the system will follow the path of least resistance and rush into the wide open slots. When this happens, the slots adjacent to the empty slots will be starved of their required airflow and blade temperature will rise, potentially causing performance degradation, reduction of lifetime, or failure of components. Another problem with current cooling solutions is that cooling air only enters the blades from the front. For some high performance blades, certain components such as hard drives and memory may suffer from inadequate cooling when only traditional front-to-back cooling is offered because of the blade configuration and their particular needs. There is, therefore, a need for an effective and efficient system to distribute air in a blade server system, particularly when one or more blades are removed or more complex cooling air patterns beyond traditional front-to-back flows are required.